Epoxy resin insulating material aging test method under multi-factor coupling condition

Abstract

The invention discloses an epoxy resin insulating material aging test method under a multi-factor coupling condition, and relates to the technical field of insulating material aging tests, an epoxy resin insulating material sample is prepared, an accelerated coupling model is constructed, and temperature, humidity and mechanical stress parameters required by the test are reversely deduced according to a model result; s2, performing parameter setting on the three-axis environment simulation cabin according to a result of the step S1, and establishing a temperature, humidity and force cooperative control algorithm to realize dynamic coupling among a plurality of parameters; and carrying out a periodic accelerated aging test on the epoxy resin insulating material sample, carrying out multi-dimensional aging degree evaluation, and terminating the test when the comprehensive index of the aging degree or the tangent value of the dielectric loss angle exceeds a threshold value. By establishing a multi-factor coupling action mechanism, the technical problem that the traditional aging test greatly deviates from the actual working condition is solved, and the method is particularly suitable for reliability evaluation of the epoxy insulating material used in severe environments such as extra-high voltage equipment and offshore wind power.

Description

Technical Field

[0001] This invention discloses an aging test method for epoxy resin insulation materials under multi-factor coupling conditions, which relates to the field of insulation material aging test technology. Background Technology

[0002] With economic and social development, electricity demand continues to grow rapidly, the scale of power distribution systems is constantly expanding, and the importance of the safe operation of power distribution equipment is becoming increasingly prominent. Epoxy resin has advantages such as good electrical insulation properties, excellent chemical properties, and light weight, and is widely used as the main insulation material in power grid equipment.

[0003] However, epoxy resin is prone to insulation degradation and partial discharge when operating in harsh environments such as high temperature and high humidity for extended periods. Under the combined effects of electricity, heat, and moisture, its insulation performance can significantly decrease or even be lost, leading to insulation failure in severe cases, causing short circuits or grounding faults, and threatening the safe operation of the power system. Therefore, studying the aging characteristics of epoxy resin insulation materials under high temperature and high humidity environments is beneficial for selecting the most suitable anti-aging measures, thereby extending the service life of epoxy resin insulation materials and ensuring the safe operation of the power grid.

[0004] However, traditional epoxy resin aging tests have three major drawbacks: 1) Single-factor limitation: Existing methods mostly use constant temperature and humidity chambers for single-factor damp heat aging. This method only considers temperature and humidity as single factors, failing to take into account the combined effects of mechanical stress, temperature gradient, and other factors present in actual working conditions. In practical applications, epoxy resin insulation materials often bear multiple stresses simultaneously, and single-factor tests cannot accurately reflect the aging process of materials under complex environments. 2) Acceleration ratio distortion: The conventional Arrhenius equation only considers temperature as a single variable and cannot reflect the aging mechanism under the synergistic effect of multiple factors such as damp heat and mechanical stress. This leads to a large deviation between the acceleration ratio obtained in the test and the actual situation, and cannot accurately predict the aging rate of materials in actual use. 3) Single evaluation dimension: Existing standards mostly focus on changes in electrical properties (such as dielectric strength) and lack online monitoring of microstructure evolution (such as changes in crosslinking degree). Changes in the microstructure of materials have a significant impact on their macroscopic properties, and a single-dimensional evaluation cannot fully understand the performance changes during the aging process of materials.

[0005] Based on the above, an aging test method for epoxy resin insulation materials under high temperature and high humidity conditions is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an aging test method for epoxy resin insulation materials under high temperature and high humidity conditions, so as to solve the problems in the background art.

[0007] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: An aging test method for epoxy resin insulation materials under multi-factor coupling conditions, implemented in a triaxial environmental simulation chamber, includes the following steps: Step S1: Prepare epoxy resin insulation material samples, construct an accelerated coupling model, and deduce the required temperature, humidity, and mechanical stress parameters for the test based on the model results. Step S2: Set the parameters of the triaxial environment simulation chamber according to the results of step S1, and establish a "temperature, humidity, force" collaborative control algorithm to realize the dynamic coupling between multiple parameters; Step S3: Conduct periodic accelerated aging tests on epoxy resin insulation material samples and evaluate the degree of aging in multiple dimensions. When the comprehensive aging index or dielectric loss tangent exceeds the threshold, the test is terminated.

[0008] Preferably, the triaxial environmental simulation chamber includes a temperature control system, a humidity control system, and a mechanical loading module; the temperature control system includes a heating wire, a semiconductor cooling chip, and multiple high-precision temperature sensors; the humidity control system includes a dual-pressure humidity generator and multiple high-precision humidity sensors. The dual-pressure humidity generator includes a high-pressure chamber and a low-pressure chamber. Saturated humid air in the high-pressure chamber is depressurized and then enters the low-pressure chamber. By controlling the pressure difference between the high-pressure chamber and the low-pressure chamber, the humidity inside the simulation chamber is precisely adjusted; the mechanical loading module adopts a motor servo loading system, which supports static holding and cyclic loading modes to achieve precise control of dynamic loads.

[0009] Preferably, the triaxial environment simulation chamber is equipped with a central control system based on industrial Ethernet, which communicates with the temperature control system, humidity control system and mechanical loading module to achieve centralized management and coordinated control of the temperature control system, humidity control system and mechanical loading module. The central control system is based on the "temperature, humidity and force" coordinated control algorithm to uniformly schedule and precisely control the three to ensure that the temperature, humidity and mechanical load in the simulation chamber change precisely according to the predetermined program.

[0010] Preferably, the triaxial environment simulation chamber is equipped with dielectric sensors and fiber optic strain gauges.

[0011] Preferably, in step S1, the coupling model is: ; in, As an acceleration factor, To accelerate the comparison of relative humidity under test conditions and actual use conditions, This is a humidity-related index. For activation energy, The gas constant is... To accelerate the temperature under the conditions, For actual conditions, regarding temperature, Mechanical loads under acceleration conditions, Mechanical loads under actual use conditions. This is the mechanical load correction factor.

[0012] Preferably, in step S2, the "temperature, humidity, and force" coordinated control algorithm is as follows: Based on the target values ​​set for each stage before the experiment, a synergy ratio adjustment factor is introduced, and change rules are formulated. During the experiment, the monitoring module continuously acquires the actual values ​​of the current temperature, humidity and mechanical load, calculates the corresponding errors, and adjusts each factor according to the errors.

[0013] Preferably, the change rule is: for every increase in temperature... T The target humidity value is adjusted to: H=δ T b The target value for the mechanical load is adjusted as follows: F=δ T k ; in, H The change in humidity. T The amount of temperature change, δ As a regulating factor, b For every 10°C increase in temperature, humidity increases. b %RH; F This represents the change in mechanical load. k This represents the percentage change in mechanical load for every 10°C increase in temperature.

[0014] Preferably, the factors are adjusted as follows: Regarding temperature regulation, if Start the heating device and set the heating power to: ;in, For heating power, This is the temperature regulation coefficient. For temperature error; if If the refrigeration unit is activated, the refrigeration power setting method is the same as the heating power setting. For humidity control, if The humidity is increased by a dual-pressure humidity generator, and the humidity adjustment is set as follows: ;in, This represents the change in humidity. Humidity adjustment coefficient, This is due to humidity error; if If dehumidification measures are taken, the method for determining the amount of dehumidification is the same as that for humidity regulation. For mechanical load adjustment, if Then increase the load output, and set the load amount as follows: ; in, For load size, This is the mechanical load adjustment coefficient. For mechanical load error; if If the load is reduced, the amount of reduction is set in the same way as the amount of load.

[0015] Preferably, in step S3, the accelerated aging test process specifically includes: Moist heat penetration stage: Pre-set in a high temperature and high humidity environment for 24 hours to allow moisture to penetrate into the interior of the material; The damp-heat-mechanical coupling stage involves applying mechanical stress to bring the stress level close to 80% of the material's yield strength, simulating the stress level the material experiences in actual use, and accelerating the material's aging process. Cyclic impact phase: Temperature cycling is performed, with a temperature range of -40~150℃. Each cycle includes 3 condensation processes. Through drastic temperature changes and condensation formation, the extreme environment that the material may encounter in actual working conditions is simulated.

[0016] Preferably, in step S3, the multi-dimensional aging degree assessment method is as follows: Monitoring materials using dielectric sensors embedded in a triaxial environment simulation chamber The rate of change is used to monitor the propagation of microcracks inside the material using fiber optic strain gauges; Periodically take material samples for testing and calculate the comprehensive aging index. ; In-situ infrared technology was used to detect the internal COC fracture. AFM analysis was used to analyze nanoscale hydrolysis pits on the material surface.

[0017] Preferred, ; in, The comprehensive index of aging. These are the weighting coefficients. This represents the change in bending strength. This is the change in glass transition temperature. The carbonyl index is measured by infrared spectroscopy. This represents the change in dielectric loss.

[0018] The beneficial effects of this invention are: I. The present invention provides an aging test method for epoxy resin insulation materials under multi-factor coupling conditions. The present invention constructs a multi-physics field coupling test device and adopts an improved acceleration model, which greatly shortens the test cycle and increases the acceleration ratio by 3 to 5 times compared with traditional methods. At the same time, the error of the constructed loading coupling model is ≤15%, compared with the error of the single-factor model >40%, which greatly improves the accuracy of predicting the material life.

[0019] II. This invention provides an aging test method for epoxy resin insulation materials under multi-factor coupling conditions. The method protected by this invention establishes a multi-dimensional evaluation system covering multiple levels, including online monitoring, offline analysis, and microscopic characterization. It not only focuses on electrical performance but also monitors the evolution of the material's microstructure, such as measuring the tanδ change rate in real time using an embedded dielectric sensor and detecting the breakage of COC bonds using in-situ infrared spectroscopy, thus comprehensively understanding the material aging process. Furthermore, it proposes an aging degree comprehensive index AI, which quantifies the degree of material aging by weighting dielectric loss, flexural strength, glass transition temperature, and carbonyl index, providing a more scientific standard for material performance evaluation.

[0020] Third, this invention provides an aging test method for epoxy resin insulation materials under multi-factor coupling conditions. By establishing a multi-factor coupling mechanism, this invention solves the technical problem of large deviation between traditional aging tests and actual working conditions, providing a practical solution for the reliability assessment of epoxy insulation materials used in harsh environments such as ultra-high voltage equipment and offshore wind power, and promoting technological progress in the industry. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0023] Example 1 like Figure 1 As shown, an aging test method for epoxy resin insulation materials under multi-factor coupling conditions is implemented through a triaxial environmental simulation chamber, including the following steps: Step S1: Prepare epoxy resin insulation material samples, construct an accelerated coupling model, and deduce the required temperature, humidity, and mechanical stress parameters for the test based on the model results. Step S2: Set the parameters of the triaxial environment simulation chamber according to the results of step S1, and establish a "temperature, humidity, force" collaborative control algorithm to realize the dynamic coupling between multiple parameters; Step S3: Conduct periodic accelerated aging tests on epoxy resin insulation material samples and evaluate the degree of aging in multiple dimensions. When the comprehensive aging index or dielectric loss tangent exceeds the threshold, the test is terminated.

[0024] Example 2 like Figure 1 As shown, an aging test method for epoxy resin insulation materials under multi-factor coupling conditions is implemented through a triaxial environmental simulation chamber, including the following steps: Step S1: Prepare epoxy resin insulation material samples, construct an accelerated coupling model, and deduce the required temperature, humidity, and mechanical stress parameters for the test based on the model results. Step S2: Set the parameters of the triaxial environment simulation chamber according to the results of step S1, and establish a "temperature, humidity, force" collaborative control algorithm to realize the dynamic coupling between multiple parameters; Step S3: Conduct periodic accelerated aging tests on epoxy resin insulation material samples and evaluate the degree of aging in multiple dimensions. When the comprehensive aging index or dielectric loss tangent exceeds the threshold, the test is terminated.

[0025] The triaxial environmental simulation chamber includes a temperature control system, a humidity control system, and a mechanical loading module. The temperature control system includes a heating wire, a thermoelectric cooler, and multiple high-precision temperature sensors. The humidity control system includes a dual-pressure humidity generator and multiple high-precision humidity sensors. The dual-pressure humidity generator comprises a high-pressure chamber and a low-pressure chamber. Saturated humid air in the high-pressure chamber is depressurized before entering the low-pressure chamber. By controlling the pressure difference between the high-pressure and low-pressure chambers, the humidity within the simulation chamber is precisely adjusted. The mechanical loading module employs a motor servo loading system, supporting static holding and cyclic loading modes to achieve precise control of dynamic loads. The heating wire, thermoelectric cooler, high-precision temperature sensors, high-precision humidity sensors, high-pressure chamber, low-pressure chamber, and motor servo loading system are all existing technologies and will not be described in detail here.

[0026] The triaxial environment simulation chamber is equipped with a central control system based on industrial Ethernet, which communicates with the temperature control system, humidity control system and mechanical loading module to achieve centralized management and coordinated control of the temperature control system, humidity control system and mechanical loading module. The central control system is based on the "temperature, humidity and force" coordinated control algorithm to uniformly schedule and precisely control the three to ensure that the temperature, humidity and mechanical load in the simulation chamber change precisely according to the predetermined program.

[0027] The triaxial environment simulation chamber is equipped with embedded dielectric sensors and fiber Bragg grating strain gauges. Both dielectric sensors and fiber Bragg grating strain gauges are existing technologies and will not be described in detail here.

[0028] In step S1, the coupling model is as follows: ; in, As an acceleration factor, To accelerate the comparison of relative humidity under test conditions and actual use conditions, This is a humidity-related index. For activation energy, The gas constant is... To accelerate the temperature under the conditions, For actual conditions, regarding temperature, Mechanical loads under acceleration conditions, Mechanical loads under actual use conditions. This is the mechanical load correction factor.

[0029] In step S2, the "temperature, humidity, and force" coordinated control algorithm is as follows: Based on the target values ​​set for each stage before the experiment, a synergy ratio adjustment factor is introduced, and change rules are formulated. During the experiment, the monitoring module continuously acquires the actual values ​​of the current temperature, humidity and mechanical load, calculates the corresponding errors, and adjusts each factor according to the errors.

[0030] Preferably, the change rule is: for every increase in temperature... T The target humidity value is adjusted to: H=δ T b The target value for the mechanical load is adjusted as follows: F=δ T k ; in, H The change in humidity. T The amount of temperature change, δ As a regulating factor, b For every 10°C increase in temperature, humidity increases. b %RH; F This represents the change in mechanical load. k This represents the percentage change in mechanical load for every 10°C increase in temperature.

[0031] The adjustment of each factor is as follows: Regarding temperature regulation, if Start the heating device and set the heating power to: ;in, For heating power, This is the temperature regulation coefficient. For temperature error; if If the refrigeration unit is activated, the refrigeration power setting method is the same as the heating power setting. For humidity control, if The humidity is increased by a dual-pressure humidity generator, and the humidity adjustment is set as follows: ;in, This represents the change in humidity. Humidity adjustment coefficient, This is due to humidity error; if If dehumidification measures are taken, the method for determining the amount of dehumidification is the same as that for humidity regulation. For mechanical load adjustment, if Then increase the load output, and set the load amount as follows: ; in, For load size, This is the mechanical load adjustment coefficient. For mechanical load error; if If the load is reduced, the amount of reduction is set in the same way as the amount of load.

[0032] Specifically, in step S3, the accelerated aging test process is as follows: Moist heat penetration stage: Pre-set in a high temperature and high humidity environment for 24 hours to allow moisture to penetrate into the interior of the material; The damp-heat-mechanical coupling stage involves applying mechanical stress to bring the stress level close to 80% of the material's yield strength, simulating the stress level the material experiences in actual use, and accelerating the material's aging process. Cyclic impact phase: Temperature cycling is performed, with a temperature range of -40~150℃. Each cycle includes 3 condensation processes. Through drastic temperature changes and condensation formation, the extreme environment that the material may encounter in actual working conditions is simulated.

[0033] In step S3, the multi-dimensional aging assessment method is as follows: Monitoring materials using dielectric sensors embedded in a triaxial environment simulation chamber The rate of change is used to monitor the propagation of microcracks inside the material using fiber optic strain gauges; Periodically take material samples for testing and calculate the comprehensive aging index. ; In-situ infrared technology is used to detect the internal COC bond fracture. COC bonds are an important component of the molecular structure of materials, and their fracture is one of the important microscopic characteristics of material aging. Through in-situ infrared detection, the changes of COC bonds in the material during the aging process can be directly observed, allowing for a deeper understanding of the aging mechanism of materials at the molecular level. AFM was used to analyze nanoscale hydrolysis pits on the surface of materials. During the aging process, nanoscale hydrolysis pits form on the surface of materials due to hydrolysis and other processes. AFM can perform high-resolution imaging and analysis of these microscopic surface features, further revealing the microscopic process of material aging.

[0034] in, ; in, The comprehensive index of aging. These are the weighting coefficients. This represents the change in bending strength. This is the change in glass transition temperature. The carbonyl index is measured by infrared spectroscopy. This represents the change in dielectric loss.

[0035] The change in dielectric loss is recorded by the embedded dielectric sensor. The data is organized chronologically and calculated for different stages. The difference, thus obtaining .

[0036] The change in bending strength is calculated by taking samples out of the test environment at certain time intervals, testing their bending strength using a universal testing machine, comparing the bending strength at different aging stages with the initial bending strength, and then calculating the change in bending strength.

[0037] The change in glass transition temperature is determined by differential scanning calorimetry (DSC) on samples at different aging stages. DSC can accurately measure the heat flow change of the material during heating or cooling, thereby determining the glass transition temperature. By comparing the glass transition temperatures at different stages, the change in glass transition temperature is obtained.

[0038] The carbonyl index was determined by analyzing the sample using Fourier transform infrared spectroscopy (FTIR). FTIR can identify the vibrational absorption peaks of specific chemical bonds in the molecular structure of materials. By measuring the intensity of the carbonyl (C=O) related absorption peaks and comparing them with standard spectra or spectra in the initial state, the change in carbonyl index was calculated.

[0039] The beneficial effects of this invention are: I. The present invention provides an aging test method for epoxy resin insulation materials under multi-factor coupling conditions. The present invention constructs a multi-physics field coupling test device and adopts an improved acceleration model, which greatly shortens the test cycle and increases the acceleration ratio by 3 to 5 times compared with traditional methods. At the same time, the error of the constructed loading coupling model is ≤15%, compared with the error of the single-factor model >40%, which greatly improves the accuracy of predicting the material life.

[0040] II. This invention provides an aging test method for epoxy resin insulation materials under multi-factor coupling conditions. The method protected by this invention establishes a multi-dimensional evaluation system covering multiple levels, including online monitoring, offline analysis, and microscopic characterization. It not only focuses on electrical performance but also monitors the evolution of the material's microstructure, such as measuring the tanδ change rate in real time using an embedded dielectric sensor and detecting the breakage of COC bonds using in-situ infrared spectroscopy, thus comprehensively understanding the material aging process. Furthermore, it proposes an aging degree comprehensive index AI, which quantifies the degree of material aging by weighting dielectric loss, flexural strength, glass transition temperature, and carbonyl index, providing a more scientific standard for material performance evaluation.

[0041] Third, this invention provides an aging test method for epoxy resin insulation materials under multi-factor coupling conditions. By establishing a multi-factor coupling mechanism, this invention solves the technical problem of large deviation between traditional aging tests and actual working conditions, providing a practical solution for the reliability assessment of epoxy insulation materials used in harsh environments such as ultra-high voltage equipment and offshore wind power, and promoting technological progress in the industry.

[0042] Example 3 Aging tests were conducted on epoxy castable refractory materials used in power transformers, such as... Figure 1 As shown, the details are as follows: S1. Sample Preparation: Strictly follow IEC 60893 standard to prepare standard test pieces with dimensions of 100×100×3mm. Thoroughly mix epoxy resin, curing agent, and various additives in a specific ratio, using a vacuum casting process to eliminate air bubbles generated during mixing, ensuring the uniformity and density of the test piece. Curing is carried out under specific temperature and time conditions to ensure stable test piece performance.

[0043] Test parameter settings Before conducting accelerated aging tests, researchers determine a target acceleration factor based on the test cycle requirements and the actual application scenario of the materials. For example, if the goal is to complete the aging process that would normally take years to observe within a few months, an AF value that meets this target needs to be set. In this embodiment, AF=5 is set, based on the known activation energy Ea, humidity sensitivity coefficient n, mechanical stress correction factor m, and gas constant R of the material. Referring to the actual operating temperature of a power transformer at 90℃, the required temperature, humidity, and mechanical stress parameters for the test are derived according to the accelerated model. The test temperature is designed to be 120℃, the humidity is set to 95%RH, and the mechanical stress is set to 6MPa.

[0044] S2. Parameter settings were configured for the triaxial environmental simulation chamber. The test temperature was set to 120℃, and the temperature fluctuation was controlled within ±0.5℃ using a PID algorithm within the temperature control system. The humidity was set to 95% RH, with periodic condensation simulation included. A dual-pressure humidity generator was used to simulate periodic condensation. The mechanical loading module, driven by a servo motor, continuously applied a bending stress of 6MPa, with feedback from a high-precision force sensor to ensure the accuracy and stability of the loading force. In subsequent experiments, a coordinated control algorithm for temperature, humidity, and force was used. For every 10℃ increase in temperature, the RH was increased by 5%, and the mechanical load was adjusted according to a specific pattern to more realistically simulate the actual working state of materials or equipment under complex environments. This algorithm enables precise coordinated control of multiple physical field parameters, providing more realistic environmental conditions for the experiment.

[0045] S3. Test cycle arrangement: Each test cycle consists of 24 hours, and each cycle includes the following three phases: 8-hour high temperature and high humidity: The test piece is placed in a triaxial environmental simulation chamber with a temperature of 120℃ and a humidity of 95% RH, allowing the test piece to fully experience the effects of high temperature and high humidity, promoting rapid penetration of moisture into the material and accelerating the aging process. This stage mainly simulates the long-term operation of a power transformer under high temperature and high humidity conditions.

[0046] 12-hour damp-heat-mechanical coupling: The temperature was lowered to 90℃, the humidity was adjusted to 85%RH, and a bending stress of 6MPa was applied simultaneously to simulate the multi-stress coupling environment of a transformer during normal operation. This stage comprehensively considers the synergistic effects of temperature, humidity, and mechanical stress, more realistically simulating the complex operating conditions of power transformers in actual operation.

[0047] 4-hour low-temperature shock: The test piece is placed in an environment of -40℃ to conduct a low-temperature shock test, simulating the sudden temperature change of a transformer during start-up and shutdown. This process simulates the low-temperature environment that a power transformer may encounter in actual operation, further accelerating the material aging process and detecting the performance changes of the material under extreme temperature changes.

[0048] During the experiment, experimental monitoring and data collection were conducted. Online monitoring: The tanδ change rate of the specimen is measured in real time using an embedded dielectric sensor, the propagation of microcracks is monitored by a fiber optic strain gauge, and the data is transmitted to the data acquisition system in real time.

[0049] Offline analysis: At regular intervals, the sample is taken out for offline analysis. The aging index AI is calculated by measuring the dielectric loss, flexural strength, glass transition temperature and carbonyl index of the sample.

[0050] Taking the end of the first experimental cycle as an example, the data calculation is as follows: Dielectric loss data acquisition and calculation: The rate of change of tanδ of the sample collected by the embedded dielectric sensor during the cycle is obtained. The initial tanδ is 0.01, and it is 0.012 at the end of the cycle. The dielectric loss is then calculated using the dielectric loss calculation formula. ; Bending strength data acquisition and calculation: The specimen was removed and a universal testing machine was used to test its bending strength. The initial bending strength was 100 MPa, and the measured value at the end of the cycle was 95 MPa. The change in bending strength was then calculated. ; Glass transition temperature data acquisition and calculation: Differential scanning calorimetry (DSC) was used to measure the glass transition temperature. The initial glass transition temperature was 150℃, and it was 148℃ at the end of the cycle. The change in glass transition temperature was then calculated. ; Carbonyl index data acquisition and calculation: The sample was analyzed using Fourier transform infrared spectroscopy (FTIR), and the carbonyl index change was calculated. The initial carbonyl index was 0.1, and it was 0.12 at the end of the period. The total change in carbonyl index was then calculated. =0.12-0.1=0.02; Substituting the above data into the formula for calculating the comprehensive aging index, we get AI = 0.4122.

[0051] Microscopic characterization: In-situ infrared spectroscopy is used regularly to detect the breakage of COC bonds, and atomic force microscopy is used to analyze the nanoscale hydrolysis pits on the surface to explore the changes in the microstructure of the material in depth.

[0052] At the end of each cycle, a comprehensive aging index is calculated, and termination conditions are determined. AIThe test automatically terminates when the AI ​​index is ≥0.7 or the dielectric loss tangent is ≥0.03. The AI ​​index reflects the overall aging status of the material; when it reaches a certain threshold, it indicates that the material is already severely aged. An increase in the dielectric loss tangent also signifies a deterioration in the material's electrical performance. By setting these two termination conditions, the test can be terminated in a timely manner, avoiding the waste of resources caused by excessive testing, while ensuring that the test results accurately reflect the performance state of the material when it reaches a certain degree of aging.

[0053] After 2000 hours of accelerated testing, the test results showed an 89.7% agreement with the sampling data of transformers that had been in operation for 8 years, with an error of ≤15%. This result demonstrates that the accelerated aging test model constructed in this invention can effectively simulate the aging process of epoxy castable refractory in power transformers during actual operation. The test results exhibit high reliability and correlation with actual conditions, providing strong technical support for the life assessment and maintenance of power transformers.

[0054] Therefore, this invention provides an aging test method for epoxy resin insulation materials under multi-factor coupling conditions. By establishing a multi-factor coupling mechanism, it solves the technical problem of large deviations between traditional aging tests and actual working conditions. At the same time, it establishes a multi-dimensional evaluation system covering multiple levels, including online monitoring, offline analysis, and microscopic characterization. It not only focuses on electrical performance but also monitors the evolution of the material's microstructure. It is particularly suitable for reliability assessment of epoxy insulation materials used in harsh environments such as ultra-high voltage equipment and offshore wind power.

[0055] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for aging test of epoxy resin insulation materials under multi-factor coupling conditions, characterized in that: This is achieved through a three-axis environmental simulation chamber, including the following steps: Step S1: Prepare epoxy resin insulation material samples, construct an accelerated coupling model, and deduce the required temperature, humidity, and mechanical stress parameters for the test based on the model results. Step S2: Set the parameters of the triaxial environment simulation chamber according to the results of step S1, and establish a "temperature, humidity, force" collaborative control algorithm to realize the dynamic coupling between multiple parameters; Step S3: Conduct periodic accelerated aging tests on epoxy resin insulation material samples and evaluate the degree of aging in multiple dimensions. When the comprehensive aging index or dielectric loss tangent exceeds the threshold, the test is terminated.

2. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 1, characterized in that: The triaxial environmental simulation chamber includes a temperature control system, a humidity control system, and a mechanical loading module. The temperature control system includes a heating wire, a semiconductor cooling chip, and multiple high-precision temperature sensors. The humidity control system includes a dual-pressure humidity generator and multiple high-precision humidity sensors. The dual-pressure humidity generator includes a high-pressure chamber and a low-pressure chamber. Saturated humid air in the high-pressure chamber is depressurized and then enters the low-pressure chamber. By controlling the pressure difference between the high-pressure chamber and the low-pressure chamber, the humidity inside the simulation chamber is precisely adjusted. The mechanical loading module adopts a motor servo loading system, which supports static holding and cyclic loading modes to achieve precise control of dynamic loads.

3. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 2, characterized in that: The triaxial environment simulation chamber is equipped with a central control system based on industrial Ethernet, which communicates with the temperature control system, humidity control system and mechanical loading module to achieve centralized management and coordinated control of the temperature control system, humidity control system and mechanical loading module. The central control system is based on the "temperature, humidity and force" coordinated control algorithm to uniformly schedule and precisely control the three to ensure that the temperature, humidity and mechanical load in the simulation chamber change precisely according to the predetermined program.

4. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 3, characterized in that: The triaxial environment simulation chamber is equipped with dielectric sensors and fiber optic strain gauges.

5. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 4, characterized in that: In step S1, the coupling model is as follows: ； in, As an acceleration factor, To accelerate the comparison of relative humidity under test conditions and actual use conditions, This is a humidity-related index. For activation energy, The gas constant is To accelerate the temperature under the conditions, For actual conditions, regarding temperature, Mechanical loads under acceleration conditions, Mechanical loads under actual use conditions. This is the mechanical load correction factor.

6. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 5, characterized in that: In step S2, the "temperature, humidity, and force" coordinated control algorithm is as follows: Based on the target values ​​set for each stage before the experiment, a synergy ratio adjustment factor is introduced, and a change rule is formulated. During the experiment, the monitoring module continuously acquires the actual values ​​of the current temperature, humidity and mechanical load, calculates the corresponding errors, and adjusts each factor according to the errors.

7. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 6, characterized in that: The rule of change is: for every increase in temperature... T The target humidity value is adjusted to: H=δ T b The target value for the mechanical load is adjusted as follows: F=δ T k ;in, H The change in humidity. T The amount of temperature change, δ As a regulating factor, b For every 10°C increase in temperature, humidity increases. b %RH; F This represents the change in mechanical load. k This represents the percentage change in mechanical load for every 10°C increase in temperature.

8. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 7, characterized in that: The adjustment of the factors is as follows: Regarding temperature regulation, if Start the heating device and set the heating power to: ;in, For heating power, This is the temperature regulation coefficient. For temperature error; if If the refrigeration unit is activated, the refrigeration power setting method is the same as the heating power setting. For humidity control, if The humidity is increased by a dual-pressure humidity generator, and the humidity adjustment is set as follows: ;in, This represents the change in humidity. This is the humidity adjustment coefficient. This is due to humidity error; if If dehumidification measures are taken, the method for determining the amount of dehumidification is the same as that for humidity regulation. For mechanical load adjustment, if Then increase the load output, and set the load amount as follows: ; in, For load size, This is the mechanical load adjustment coefficient. For mechanical load error; if If the load is reduced, the amount of reduction is set in the same way as the amount of load.

9. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 8, characterized in that: In step S3, the accelerated aging test process specifically includes: Moist heat penetration stage: Pre-set in a high temperature and high humidity environment for 24 hours to allow moisture to penetrate into the interior of the material; The damp-heat-mechanical coupling stage involves applying mechanical stress to bring the stress level close to 80% of the material's yield strength, simulating the stress level the material experiences in actual use, and accelerating the material's aging process. Cyclic impact phase: Temperature cycling is performed, with a temperature range of -40~150℃. Each cycle includes 3 condensation processes. Through drastic temperature changes and condensation formation, the extreme environment that the material may encounter in actual working conditions is simulated.

10. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 9, characterized in that: In step S3, the multi-dimensional aging degree assessment method is as follows: Monitoring materials using dielectric sensors embedded in a triaxial environment simulation chamber The rate of change is used to monitor the propagation of microcracks inside the material using fiber optic strain gauges. Periodically take material samples for testing and calculate the comprehensive aging index. ; In-situ infrared technology was used to detect the internal COC fracture. AFM analysis was used to analyze nanoscale hydrolysis pits on the material surface.

11. The aging test method for epoxy resin insulation materials under multi-factor coupling conditions according to claim 10, characterized in that: ； in, The comprehensive index of aging. These are the weighting coefficients. This represents the change in bending strength. This is the change in glass transition temperature. The carbonyl index is measured by infrared spectroscopy. This represents the change in dielectric loss.

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